JPS5828140B2 - Residual pressure mechanism of brake master cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mask cylinder residual pressure mechanism that applies a constant brake fluid pressure to a brake system in a vehicle such as an automobile.

In general, brake fluid in automobile brake systems is maintained at a pressure slightly higher than atmospheric pressure at all times, raising the boiling point temperature of the brake fluid and increasing the heat capacity of the brake fluid, causing vapor lock or preventing brake fluid from entering the brake system. Prevents air from being sucked in.

The brake fluid pressure for this purpose is called residual pressure, and the mechanism that applies this residual pressure is a residual pressure mechanism.

Conventionally, this type of residual pressure mechanism has a piston 1 biased by a return spring 14, as shown in FIG.
A valve chamber 4 communicating with a brake system on the side of a wheel cylinder (not shown) is formed in a boss portion a integrated with a mask cylinder 3 having a reservoir tank 2, etc., and an elastic reed is provided within this valve chamber 4 by a set spring 5. A residual pressure mechanism 10 is configured by urging a valve body 6 made up of a valve 8 and its holder 7 so as to come into pressure contact with a seat portion 9a of a valve plug 9.

During brake operation, pressure fluid introduced into the valve chamber 4 from the hydraulic pressure generation chamber 11 through the first communication hole 12 is pushed open the lip 8a of the reed valve 8 through the hole 7a of the holder 7, and is then passed through the valve plug 9. It flows to the wheel cylinder side through the second communication hole 13 to operate the brake.

When releasing the brake, the holding body γ is used together with the reed valve 8.
is pushed up against the force of the set spring 5 to cause the brake fluid to flow back into the hydraulic pressure generating chamber 11.

By appropriately determining the spring constant of the set spring 5, residual pressure is generated while preventing the pressure on the wheel cylinder side from dropping below a certain set value.

By the way, in such a conventional residual pressure mechanism, especially in a factory assembly line, air in the brake system is sucked out from above the reservoir tank 2 by a vacuum pump during brake assembly to create a vacuum state in the system. Later, a method is used in which the brake system is filled with brake fluid using a switching valve between a vacuum pump and a brake fluid reservoir.

However, during this vacuum suction, before the residual pressure mechanism 10 acts and the air from the wheel cylinder side is completely removed, the seat 9a and the j-de valve 8 come into pressure contact and the wheel cylinder side is not completely evacuated. Otherwise, the suction time may become longer.

Therefore, even if the brake fluid is pumped after this, there are problems such as it is difficult to completely fill the brake system to the end of the brake system on the wheel cylinder side.

In view of this conventional situation, the present invention has a residual pressure mechanism in which, before vacuum filling with brake fluid, the fluid pressure generation chamber side and the wheel cylinder side are brought into communication to completely and quickly perform vacuum suction. After the brake fluid is vacuum-filled, the valve body performs the same valve function as a normal residual pressure mechanism to ensure a reliable residual pressure function.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, in which the same parts as those of the conventional structure are denoted by the same reference numerals.

That is, in the present invention, as illustrated in FIG. 2, a valve body 6 consisting of an elastic reed valve 8 and its holder 7 is elastically mounted in a valve chamber 4 with a set spring 5. The holder mounting portion 8b of the elastic reed valve 8 is formed into a cylindrical shape, and two annular protrusions 20 and 21 are formed on the inner periphery of the holder mounting portion 8b. is held between the lips 8a and the holding body 7 is held apart from the lip 8a.

These protrusions 20 and 21 have a higher holding strength than the set spring 5, and a lower holding strength than the hydraulic pressure during vacuum filling of brake fluid, and the force of the set spring 5 is set before the brake fluid is filled. While firmly holding the holding body 7 in a state separated from the lip 8a, the first communication hole 12 and the second communication hole 13, and therefore the brake system on the wheel cylinder side (not shown) and the mask cylinder 3 The hydraulic pressure generating chamber 11 is communicated with the hydraulic pressure generating chamber 11.

Further, the lower surfaces of these protrusions 20.21 are formed flat so as to be in surface contact with the holder 7, and as described above, when the holder 7 is held apart from the lip 8a, the valve body 6 Even if the holder 7 vibrates, the holder 7 will not be pulled out.

In addition, when brake fluid is vacuum filled and the holder 7 is used in close contact with the lip 8a, large amounts of pressure are generated between the hydraulic pressure generation chamber 11 side of the holder 7 and the wheel cylinder side due to repeated generation of hydraulic pressure due to brake operation. No differential pressure occurs
- The door valve 8 and the holder 7 operate integrally, and the holder 7 does not come out.

With the above configuration, when vacuum suction is applied to the brake system when filling brake fluid, the residual pressure mechanism 1
The holding body 7 of the valve body 6 of No. 0 is held apart from the lip 8a of the elastic reed valve 8 by projections 20° 21, and the brake system on the wheel cylinder side and the hydraulic pressure generation chamber 11 are in communication with each other. Therefore, the brake system on the wheel cylinder side can be completely and quickly evacuated without leaving any air in the brake system.

After this evacuation, when the brake fluid is pressurized and filled, the brake fluid pressure causes the holder 7 to climb over the protrusion 21 and come into close contact with the lip 8a as shown in FIG. The brake fluid pushes open the lip 8a through the hole 7a of the holder 7, and is supplied into the brake system on the wheel cylinder side. After filling the brake fluid, the force of the set spring 5 and the reed valve 8 are
This action ensures a predetermined residual pressure within the brake system.

Therefore, after this brake fluid is filled, the residual pressure function can be properly exerted during brake operation, similar to the conventional brake fluid.

In the above embodiment, the projections 20.21 are formed in an annular shape, but in some cases, a plurality of projections 20.21 may be formed intermittently on the same circumference in consideration of the force of the set spring 5. good.

As described above, according to the present invention, the retaining body of the valve body of the residual pressure mechanism is held apart from the lip of the elastic reed valve in the state before brake fluid is filled, and when the brake fluid is filled, it is held by the brake fluid filling pressure. Since the holding body can be automatically set to the proper operating position where it is in close contact with one knob, when the vacuum is drawn when filling the flake fluid, the brake system is completely and quickly evacuated and the brakes are removed. It can be filled with brake fluid, and after being filled with brake fluid, it can perform the same residual pressure function as a conventional residual pressure mechanism.
As a result, the brake function can be further improved, and reliability can be improved, which is an excellent practical effect.

[Brief explanation of drawings]

Figure 1 is a sectional view of a brake master cylinder equipped with a conventional residual pressure mechanism, Figure 2 is a sectional view of the residual pressure mechanism of the present invention before it is filled with brake fluid, and Figure 3 is a sectional view of the same brake master cylinder after it is filled with brake fluid. It is a sectional view showing a state. 3...Mask cylinder, 4...Valve chamber,
5... Set spring, 6... Valve body, 7... Holding body, 8... Elastic reed valve, 8a... Lip, 10...Residual pressure mechanism, 11...Liquid pressure generation chamber, 12...First
Communication hole, 13...Second communication hole, 20.21
······protrusion.

Claims (1)

[Scope of Claims] 1. An elastic reed valve is provided in a valve chamber that communicates with the hydraulic pressure generating chamber of the master cylinder through a first communication hole and with the brake system on the wheel cylinder side through a second communication hole. In a configuration in which a valve body consisting of a holder and a holder thereof is elastically mounted via a set spring, a protrusion is formed on the inner periphery of the elastic reed valve to hold the holder at a distance from the elastic reed valve; The retaining strength of the protrusion is set to be higher than the spring force and lower than the pumping fluid pressure during vacuum filling of brake fluid, and before vacuum filling of brake fluid, the holding body is connected to an elastic reed valve. A residual pressure mechanism for a brake mask cylinder, characterized in that a first communication hole and a second communication hole are communicated with each other by being spaced apart from each other. 2. The brake mask cylinder according to claim 1, wherein the projection is formed flat so that its lower surface is in surface contact with the holder, and prevents the holder from coming off against repeated generation of hydraulic pressure. Residual pressure mechanism.